A gas turbine engine, for example, a turbofan jet engine, includes a fan coupled to a rotatable shaft. As the fan rotates, ambient air is drawn into the engine through an inlet thereof. A portion of the drawn air passes through a bypass flow path and escapes through an exhaust port of the engine and creates thrust that propels a vehicle. Another portion of the drawn air is directed through one or more compressors that compress and pressurize the air. The compressed air is directed to a combustor in which the compressed air is combined with a fuel and ignited. Such ignition causes combustion of the fuel and the compressed air, and produces rapidly expanding gasses. The gasses pass through a turbine that includes one or more turbine stages coupled to the shaft, and are exhausted through the exhaust port. The gasses rotate the turbine stages, which then causes the shaft to rotate. Rotation of the shaft rotates the fan to draw in more ambient air into the inlet port of the engine.
Temperature sensors may be disposed in the turbine to measure the temperature of the gasses passing therethrough. A controller monitors such temperature measurements during operation of the gas turbine engine to adjust operation of the compressors and/or combustor so to ensure the engine operates efficiently and to reduce risk of engine damage, for example, from overheating.
During development, temperature rakes, each rake having multiple sensors along the length thereof, may be distributed circumferentially about the shaft in the turbine. Temperatures acquired from the sensors in these rakes during testing of the engine can be used to monitor temperature at various points in the turbine, both radially and circumferentially, when the engine is operated under different conditions. Such detailed temperature monitoring can be used to manages engine operation so that the engine operates efficiently and within acceptable temperature ranges. The detailed temperature monitoring using rakes can also be used to develop a profile of how the temperature distribution varies in the turbine under different operating conditions of the engine.
However, the use of temperature rakes in a production engine is not feasible because it increases the costs and complexity of the turbine temperature monitoring system. Instead, one or more temperature sensors are distributed circumferentially about a portion of the rotatable shaft in the turbine, each temperature sensor placed at predetermined radial distance from the shaft. Such predetermined distance may be, for example, halfway between the shaft and a casing that surrounds the turbine.